Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

Date of Award

Fall 2009

Document Type


Degree Name

Master of Science (MS)


Department of Integrated Science and Technology


Incidences of fish kills and intersex phenomena have occurred extensively in the Shenandoah River since 2004. Pharmaceuticals including triclosan have been detected at low concentrations in the Shenandoah River. Scientists hypothesize that triclosan, an antibacterial agent, may be one of the pharmaceuticals that is responsible for fish kills and intersex phenomena. Methyl triclosan (MTS) were found in fish tissues at a significantly higher concentration in the part of the Shenandoah River where fish kills are present compared to a non-impact river. Triclosan is widely used in personal care products, such as soaps, shampoos, and toothpastes and is rinsed down the drain. It enters the aquatic environment via wastewater discharges and can accumulate in the surface waters since waters and wastewater treatment technologies do not completely remove triclosan from treated wastewater. This thesis explores an application of the system dynamics problem solving and modeling methodology to predict triclosan concentration levels in parts of the North and Middle Rivers, main tributaries of the South Fork Shenandoah River. A simulation model calculate triclosan concentrations in the North and Middle River based on numerous factors including watershed characteristics, streamflow, and removal efficiency of triclosan in wastewater treatment plants. The effect of removal efficiency in WWTPs is the most sensitive factor to the triclosan concentration levels regarding simulated results. Concentrations significantly change whether treatment systems are improved or deteriorated. Treatment technology improvement would be a significant approach to reduce triclosan concentrations in the North and Middle Rivers. For further research, the model platform could be applied to predict concentrations of triclosan or other pollutants in other rivers. However, a number of variables are needed to be modified to fulfill this purpose.